a. Field
The instant disclosure relates to catheters for infusing cardiovascular fluids or solutions into blood vessels. The infused fluids may be used for oxygen therapy to treat various tissue conditions and other ailments.
b. Background Art
Catheters are used in a variety of diagnostic and therapeutic procedures, including oxygen therapy procedures. For example, it has been found that delivering oxygen supersaturated fluid to damaged tissue (e.g., infarcted tissue after a heart attack) can help mitigate the damage and potentially facilitate tissue recovery (e.g., reducing infarct size). It is thought that infusing an oxygen supersaturated fluid (for example, saline supersaturated with oxygen or “aqueous oxygen” (AO)) onto tissue greatly facilitates diffusion of the oxygen into that tissue (e.g., diffusing oxygen into ischemic tissue).
A disadvantage of one existing system for infusing oxygen onto tissue is the need for an extracorporeal blood circuit for mixing a cardiovascular fluid (e.g., oxygen supersaturated saline) with the patient's blood to create super-oxygenated blood. In this system, AO is infused into blood flowing in a small extracorporeal circuit. The current application is the infusion of blood that is supersaturated with AO into a coronary artery after stenting for an acute myocardial infarction. The geometry of mixing AO with blood is well controlled, along with the equilibrium O2 concentration achieved in blood resulting from AO infusion. There are several important limitations with this approach. Withdrawing blood such as with a roller pump requires a separate withdrawal line, and the level of negative pressure in the line must be carefully monitored to prevent inadvertent cavitation. Platelet activation and plastic tube spallation by the roller pump are potential concerns, as is the potential thrombogenicity of the extracorporeal circuit. Finally, the extracorporeal circuit is not scalable easily to treat systemic problems, such as hemorrhagic shock and respiratory insufficiency. Very large tubings and catheters, similar to ones used for membrane oxygenators, would be required to supplement systemic oxygen needs.
The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of claim scope.